Dehydrated black olives from unfermented and alkali treated green olives

Abstract

The black dry olive is a highly regarded product that is mostly elaborated from harvested black fruits subjected to a dry-salting process. The aim of this study was to develop a new dehydrated black table olive product. Fruits of the Gordal and Hojiblanca cultivars were alkali treated and preserved in brine for several months, after which they were dehydrated at 60 °C. Among the variables assessed to avoid lactic acid fermentation of the olives (NaCl concentration, washing, temperature), only maintenance of the fruit under refrigeration (5-6 °C) succeeded in maintaining the pH of the fruit above 6 units for several months. This high pH was crucial to obtaining dark olives after the dehydration process because browning of the fruit was highly dependent on their pH level. Chemical oxidation of phenolic compounds, in particular hydroxytyrosol, was related to the first order kinetic of the darkening rate of olives. Unfermented and dried olives of the Gordal cultivar were packed and assessed by tasters that considered this new dehydrated black table olive product as acceptable for future consumers.